Acoustic device



May 21, 1935.

H, .1. ROUND ET AL ACOUSTIC DEVICE Filed April 1'7, 1928 Patented May 21, 1935 UNITED STATES PATENT OFFICE ACOUSTIC DEVICE Wal'e Application April 1'7, 1928, Serial No. 270,683 In Great Britain April 22, 1927 16 Claims.

This invention relates to acoustic devices, and more particularly to loud speakers, microphones, gramophones and the like, of the kind provided with large area conical or similar diaphragms.

In such acoustic instruments, it is frequently desirable to provide a parallel motion between the diaphragm and the support therefor, so that the coil or other driving mechanism for the said diaphragm may be free to move in the magnetic air gap of the instrument.

According to this invention the conical or similar diaphragm of an acoustic device is supported upon a central shaft by means of a plurality of spiders of paper or other suitable material.

The invention is illustrated in the accompanying drawing, in which:

Figure 1 shows in front elevation one form of construction,

Figure 2 shows a sectional side elevation of the modification shown in Figure 1, and

Figure 3 shows the small supporting spider 8 embodied in the construction shown in Figures 1 and 2.

Referring to the drawing, l is a conical diaphragm of paper or the like, having a stiffening peripheral ring 2 at its larger end and carrying at its smaller end an annular coil 3, whereby it is impulsed. In use the coil 3 is supplied with currents of acoustic frequency, and is adapted to project into a ring-shaped magnetic air gap 4 between concentric pole pieces 5, 6 (Figure 2). The diaphragm l is supported upon a central shaft I, by means of two paper spiders 8, 9, of different sizes.

The spiders 8, 9, are secured at their circumferences to the inner face of the diaphragm and are coaxially mounted upon and secured to the central shaft 1 which passes, as shown, through holes in the centres of the said spiders.

The shaft I is adapted to be screwed or otherwise fixed to any convenient part of the magnetic structure, for example, the pole piece 5, as shown in Figure 2, and in this way the diaphragm and supports are therefore rendered readily detachable.

Having now particularly described and ascertained the nature of our said invention and in what manner the same is to be performed we claim:

1. An acoustic device comprising a conical diaphragm, operating means associated with said diaphragm, and means positioned within said diaphragm and circumferentially engaging an intermediate portion thereof for supporting said diaphragm.

2, A sound reproducer comprising a conical diaphragm, driving means associated with said conical diaphragm, and supporting means located entirely within and encompassed by said conical diaphragm, said supporting means comprising the sole support for said diaphragm.

3. A sound reproducer of the electrodynamic type comprising a conical diaphragm, a driving coil connected to said diaphragm, a magnet system for cooperating with said driving coil, said magnet system comprising pole pieces forming an annular air gap, a member secured to the central pole piece of said pole pieces and extending into said diaphragm, and a plurality of spiders positioned on said member and engaging said diaphragm.

4. In a sound reproducer the combination of a conical diaphragm and means connected to said diaphragm between the apex and the base thereof for supporting said diaphragm, said means consisting of at least one circular member positioned within said diaphragm.

5. In a sound reproducer the combination of a conical diaphragm and means connected to said diaphragm between the apex and the base thereof for supporting said diaphragm, said means consisting of a rod positioned within said diaphragm and at least one spider member supported by said rod and having an annular contact within said diaphragm.

6. A sound reproducer of the electro-dynamic type comprising a conical diaphragm, a driving coil connected to said diaphragm, a magnet system for co-operating with said driving coil, said magnet system comprising a central pole piece and an outer pole piece spaced therefrom, a member removably secured to said central pole piece and extending outwardly therefrom within said diaphragm and a plurality of spiders positioned on said member and engaging said diaphragm to form the sole support therefor, said member, spiders and diaphragm forming a unit adapted to be readily removed from said sound reproducer.

7. An acoustic device including a conical diaphragm, stationary supporting structure spaced from a portion of said diaphragm which is remote from its periphery, and a thin, flat, flexible member connected between said stationary supporting structure and said diaphragm, said member comprising a body having an annular portion, a portion to be connected with said stationary supporting structure, and a plurality of radial arms extending between said annular portion and the portion to be connected with the stationary structure.

8. In an acoustic device, a conical diaphragm, a supporting rod extending into said diaphragm, and a pair of fiat spider members positioned on said rod for supporting said diaphragm.

9. A cone tympanum for a reproducer comprising a cone, a support for the cone near the apex end thereof, and means for supporting the cone near the base from the inside of the cone.

10. A cone tympanum for a reproducer comprising a truncated cone, a supporting member disposed along the axis of the cone, and connections from the inside of the cone at points near the apex and base ends to the centrally disposed supporting member.

11. In a reproducer of the character described a direct current coil, a core serving as one pole of an electromagnet, a casing serving as a second pole of said magnet, the two poles being arranged to form a circular magnetic gap, a cone supporting a movable coil disposed in said gap, an extension frem said core pole piece, and a pair of flexible connections between the inside of the cone and said pole piece extension, one of said connections being near the apex end of the cone, and the other end of said connections being near the base end of the cone.

12. In an electromagnetic sound reproducer, a projecting magnetic pole, a coil surrounding said pole, a conical diaphragm attached at its apex to said coil, a flexible planiform member secured across the base of said diaphragm, allowing substantially unitary movement or" said diaphragm and a strut mounted on said pole and secured to said member.

13. In a sound reproducer, a diaphragm comprising a cone, a flexible planiform member secured across the base of said cone, allowing sub stantially unitary movement of said cone, the stiffness of said member varying thereacross, and

a support for said member attached to the stifiest portion thereof.

14. In a sound reproducer, a diaphragm com prising a cone, a flexible planiform member secured across the base of said cone, allowing substantially unitary movement of said cone, the stiffness of said member increasing toward the center thereof, and a support attached at the center of said member.

15. In a sound reproducer, a diaphragm comprising a cone, a flexible supporting member extending across the base of said cone, allowing substantially unitary movement of said cone, and a rigid supporting member attached to said flexible supporting member adjacent its central portion, the stiffness of said flexible supporting member being greatest adjacent its attachment to said cone and said rigid supporting member.

16. An acoustic device including a conical diaphragm, a driving coil secured to said diaphragm at the apex portion thereof, stationary supporting structure spaced from a portion of said diaphragm which is remote from its periphery,

means for supporting the peripheral portion of said diaphragm, and means for centering and supporting said driving coil, said means for'centering and supporting said driving coil comprising a thin, flat, flexible member connected between said stationary supporting structureand said diaphragm, said member comprising a body having an annular portion secured to said diaphragm in the vicinity of said driving coil but spaced therefrom, a portion connected to said stationary supporting structure, and a plurality of arms extending between said annular portion and the portion connected to the'stationa'ry structure. 7

HENRY JOSEPH ROUND. NoiiL MEYER RUST.- 

